diff mbox

[v3,10/10] nf_conntrack: Use rcu_barrier()

Message ID 1245924178.24921.61.camel@localhost.localdomain
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Jesper Dangaard Brouer June 25, 2009, 10:02 a.m. UTC 
On Thu, 2009-06-25 at 11:29 +0200, Jesper Dangaard Brouer wrote:
> Should I make two different patchs?

Here is the single patch... Patrick tell me if you want it split up?


[PATCH v3 10/10] nf_conntrack: Use rcu_barrier()

From: Jesper Dangaard Brouer <hawk@comx.dk>

RCU barriers, rcu_barrier(), is inserted two places.

 In nf_conntrack_expect.c nf_conntrack_expect_fini() before the
 kmem_cache_destroy().  Firstly to make sure the callback to the
 nf_ct_expect_free_rcu() code is still around.  Secondly because I'm
 unsure about the consequence of having in flight
 nf_ct_expect_free_rcu/kmem_cache_free() calls while doing a
 kmem_cache_destroy() slab destroy.

 And in nf_conntrack_extend.c nf_ct_extend_unregister(), inorder to
 wait for completion of callbacks to __nf_ct_ext_free_rcu(), which is
 invoked by __nf_ct_ext_add().  It might be more efficient to call
 rcu_barrier() in nf_conntrack_core.c nf_conntrack_cleanup_net(), but
 thats make it more difficult to read the code (as the callback code
 in located in nf_conntrack_extend.c).

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
---

 net/netfilter/nf_conntrack_expect.c |    4 +++-
 net/netfilter/nf_conntrack_extend.c |    2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)



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Comments

Patrick McHardy June 25, 2009, 2:33 p.m. UTC | #1 
Jesper Dangaard Brouer wrote:
> RCU barriers, rcu_barrier(), is inserted two places.
> 
>  In nf_conntrack_expect.c nf_conntrack_expect_fini() before the
>  kmem_cache_destroy().  Firstly to make sure the callback to the
>  nf_ct_expect_free_rcu() code is still around.  Secondly because I'm
>  unsure about the consequence of having in flight
>  nf_ct_expect_free_rcu/kmem_cache_free() calls while doing a
>  kmem_cache_destroy() slab destroy.
> 
>  And in nf_conntrack_extend.c nf_ct_extend_unregister(), inorder to
>  wait for completion of callbacks to __nf_ct_ext_free_rcu(), which is
>  invoked by __nf_ct_ext_add().  It might be more efficient to call
>  rcu_barrier() in nf_conntrack_core.c nf_conntrack_cleanup_net(), but
>  thats make it more difficult to read the code (as the callback code
>  in located in nf_conntrack_extend.c).

Applied, thanks Jesper.
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diff mbox

Patch

diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
index afde8f9..2032dfe 100644
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -617,8 +617,10 @@  err1:
 void nf_conntrack_expect_fini(struct net *net)
 {
 	exp_proc_remove(net);
-	if (net_eq(net, &init_net))
+	if (net_eq(net, &init_net)) {
+		rcu_barrier(); /* Wait for call_rcu() before destroy */
 		kmem_cache_destroy(nf_ct_expect_cachep);
+	}
 	nf_ct_free_hashtable(net->ct.expect_hash, net->ct.expect_vmalloc,
 			     nf_ct_expect_hsize);
 }
diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c
index 4b2c769..fef95be 100644
--- a/net/netfilter/nf_conntrack_extend.c
+++ b/net/netfilter/nf_conntrack_extend.c
@@ -186,6 +186,6 @@  void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
 	rcu_assign_pointer(nf_ct_ext_types[type->id], NULL);
 	update_alloc_size(type);
 	mutex_unlock(&nf_ct_ext_type_mutex);
-	synchronize_rcu();
+	rcu_barrier(); /* Wait for completion of call_rcu()'s */
 }
 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);